Lead exposure in early childhood linked to faster memory loss

Lead exposure in early childhood linked to faster memory loss | Image Credit: © GenZGraphics - stock.adobe.com.

A study published July 9, 2025, in Science Advances suggests that low-level lead exposure in early childhood may accelerate memory decay in children, potentially undermining cognitive development. Researchers at the Icahn School of Medicine at Mount Sinai used a delayed matching-to-sample (DMTS) task to evaluate the association between developmental lead exposure and memory retention in children aged 6 to 8 years.^1,2

The longitudinal study analyzed data from 576 participants in the Programming Research in Obesity, Growth, Environment, and Social Stressors (PROGRESS) birth cohort in Mexico City. Researchers measured lead concentrations in maternal blood during the second and third trimesters of pregnancy and in children at ages 4 to 6 years. Blood lead levels were evaluated in relation to children's performance on the DMTS task—a cognitive test used to assess working memory and attention.

The researchers applied a nonlinear modified power function model to estimate rates of forgetting. Higher childhood blood lead levels, even at a median of 1.7 µg/dL, were associated with significantly faster forgetting rates (β = −0.05; 95% CI, −0.09 to −0.01) after adjusting for maternal IQ, child age, and sex. Prenatal lead levels showed nonsignificant associations in the same direction. Higher maternal IQ and older child age were significantly associated with better memory retention.

"Children with higher levels of blood lead forgot the test stimulus faster than those with low blood lead levels," said Robert Wright, MD, MPH, Ethel H. Wise chair of the Department of Environmental Medicine and co-director of the Institute for Exposomic Research at Mount Sinai.

The DMTS task was chosen for its translational value; it is widely used in animal models of neurotoxicology, allowing for cross-species comparisons, according to the authors. In the task, children were shown a picture and then asked to identify it from 3 options after a delay of up to 32 seconds. Performance was measured as the proportion of correct responses across varying delay intervals.

"Our work advances the current literature by incorporating operant tests—specifically the DMTS—which are commonly used in animal toxicology studies but sparse in human studies," said Jamil M. Lane, PhD, MPH, co-first author and instructor in Environmental Medicine at Mount Sinai.

Children with blood lead levels in the highest 5% of the study cohort (range, 3.9–22.8 µg/dL) demonstrated faster rates of forgetting compared with those in the lowest 5%. Performance declined predictably as blood lead levels increased from 1 to 10 µg/dL, even when adjusting for other covariates.

"The nonlinear modified power function has been validated in previous animal and human studies but is now applied in the field of environmental health," said Katherine Svensson, PhD, MS, co-first author and postdoctoral fellow in Environmental Medicine at Mount Sinai. "This new usage is important because children are exposed to many environmental chemicals, and this model provides a validated method to further assess the effect of additional environmental exposures."

The study reinforces previous findings that lead toxicity affects memory, attention, and executive functioning, even at levels below the Centers for Disease Control and Prevention’s reference value of 3.5 µg/dL. According to the authors, these findings support public health efforts to eliminate environmental sources of lead exposure, particularly in vulnerable communities.

“There may be no more important a trait than the ability to form memories. Memories define who we are and how we learn,” said Wright. “This paper breaks new ground by showing how environmental chemicals can interfere with the rate of memory formation.”

The authors emphasize the need for continued translational research to assess the neurological impact of environmental toxins using cognitive endpoints shared between animal models and human studies. The study also underscores the importance of early intervention and prevention policies aimed at mitigating lead exposure in both domestic and international contexts.

The research was supported in part by grants from the National Institutes of Health, including T32HD049311, R01ES014930, R01ES013744, and others.

References:

1. The Mount Sinai Hospital / Mount Sinai School of Medicine. Prenatal and childhood lead exposure linked to faster memory decay in children. Eurekalert. July 9 2025. Accessed July 9, 2025. https://www.eurekalert.org/news-releases/1090497

2. Svensson K, Lane JM, Chelonis JJ, et al. Developmental Pb exposure increases rate of forgetting on a delayed matching-to-sample task among Mexican children. Science Advances. 2025;11(28). doi:https://doi.org/10.1126/sciadv.adq4495

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